Hopper structure



1967 D. w. ROLLINS ETAL 3,

HOPPER STRUCTURE 7 Sheets-Sheet 1 Filed March 5, 1964 INVENTORS DALLASW. ROLLINS WILLARD E. K MP AGENT 1967 D. w. ROLLINS ETAL 3,302,979

HOPPER STRUCTURE 'T Sheets-Sheet 2 Filed March 3, 1964 INVENTORS DALLASW. ROLLINS WILLARD E. KEMP AGENT Feb. 7, 1967 Filed March 5, 1964 D. W.ROLLINS ETAL HOPPER STRUCTURE 7 Sheets-Sheet 5 INVENTORS DALLAS W.ROLLINS WILLARD E. KEMP 0/" 21 awn D. w. ROLLINS ETAL 3,302,979

Feb. 7, 1967 HOPPER STRUCTURE Filed March a, 1964 '7 Sheets-Sheet 4INVENTORS DALLAS W. ROLLINS WlLLARD E KEMP AGENT 7 Sheets-Sheet 5 D. W.ROLLINS ETAL HOPPER STRUCTURE Feb. 7, 1967 Filed March 3, 1964 INVENTORSDALLAS W, ROLLINS BY WILLARD E. KEMP AGENT 1967 D. w. ROLLINS ETAL3,302,979

HOPPER STRUCTURE '7 Sheets-Sheet 6 Filed March 5, 1964 INVENTOR. DALLASW ROLLINS BY WILLARD E. KEMP gldl (7/ AGENT 1967 D. w. ROLLINS ETAL3,302,979

HOPPER STRUCTURE Filed March 5, 1964 '7 Sheets-Sheet 7 INVENTORS DALLASW. ROLLINS WILLARD E. KEMP United States l atent' 6 3,302,979 HOPPERSTRUCTURE Dallas W.- Rollins, St. Charles, and Willard E. Kemp,

Bridgeton, Mo., assignors to ACF Industries, Incorporated, New York,N.Y., a corporation of New Jersey Filed Mar. 3, 1964, Ser. No. 349,53811 Claims. (Cl. 302-52) This invention relates to a hopper structure forconveying and unloading bulk materials and more particularly toapparatus for transporting and conveying granular or pulverulentmaterials especially of the type transported in covered hopper railwaycars.

In the unloading of granular or pulverulent materials, such as flour,sugar, cement, plastic pellets or powders, lime, and the like, a problemis presented because of the tendency of the particles to compact andadhere to each other. The movement of the railway car or other transportvehicle produces a jarring or vibratory eifect which further tends tocompact the material as it is being transported from one location toanother. I When the material is unloaded after being transported, thedischarge of such material is not of a uniform flow in many instancesdue to compacted areas, particularly in corners, and the arching orbridging of the material over the outlet openings.

In solving this problem, mechanical devices to vibrate the hoppers andshake the material loose have been employed. Also, mechanical agitatorshave been used to separate the compacted mass of material so that itwill fall freely through a bottom outlet opening. Mechanical deviceshave not been advantageous because of the size I of the covered hopperrailway cars and the relative complexity of the devices, such asagitators. In addition, the mechanical devices merely breakup thecompacted mate rial and do not speed unloading of the material.

Other attempts at solving the problem include pneumatic unloadingsystems in which a plenum chamber having an upper sloping surface isprovided along which the material to be discharged flows or slides. Airunder pressure within the plenum chamber is diifused into the materialthrough a permeable member forming the sloping surface and tends tobreakup compacted particle masses and when employed with pulverulentmaterial will fluidize a substantial portion of the pulverulent materialin the hopper structure to aid the particles in moving or sliding towardthe discharge opening. The present invention is directed particularly topneumatic unloading systems in which a plenum chamber is provided and isdefined by an upper wall or member formed of a porous or permeablematerial which permits air to seep through the material and diifuse intothe material being unloaded adjacent the .plenum chamber.

A low center of gravity in a loaded covered hopper car is highlydesirable. Such a low center of gravity is easily obtained with a hopperstructure extending downwardly a maximum extent and having a wideopening leading to the outlet structure. The clearance permitted betweenthe bottom of the outlet structure and the track limits the extent towhich a hopper sructure may extend downwardly and an outlet dischargenozzle which extends laterally outwardly from the outlet structurepermits the outlet structure beneath the hopper to utilize only aminimum vertical space.

The present invention is directed to transport vehicles and the likewhich are unloaded pneumatically and have a bottom outlet structure witha plenum chamber extending completely around the periphery of thedischarge opening in the bottom of the outlet structure. A permeablemember defines the upper portion of the plenum chamber and the materialto be unloaded pneumatically is supported on the upper surface of thepermeable member adjacent the outlet opening. As the permeable memberand plenum chamber extend around the entire inner periphery of the.outlet structure, the permeable member must be sufiiciently rigid towithstand the weight of material supported on its upper surface and toresist adequately air pressure within the plenum chamber. A permeablemember which is composed of a single membrane formed of a material, suchas a fine mesh metal or plastic mate' rial, is not s-ufiiciently rigidto withstand the weight of the material being unloaded and the airpressure within the plenum chamber over a period of time without beingundesirably large in thickness. The present permeable member is formedand constructed in such a manner as to provide sufficient rigidity evenwith a relatively large support area. A large support area for themembrane is desirable in order to obtain a maximum utilization of thecubic capacity of a covered hopper railway car and such an area isprovided when the slope of the permeable member relative to thehorizontal is relatively small and the outlet structure has a relativelylarge area.

It is an object of this invention to provide a covered hopper railwaycar having a bottom outlet structure for pneumatically unloadingmaterial in the car in which a maximum utilization is made of the cubiccapacity of the covered hopper railway car and the center of gravity ofthe loaded car is at a minimum height from the upper surface of thetrack.

Another object of this invention is the provision of a permeable wall ormember for a plenum chamber of a pneumatic outlet structure which wallhas an exposed surface along which the material to be unloaded easilyslides, is easily cleaned with strong solvents or steam, and issufliciently rigid even with a relatively large surface area.

An additional object is the provision of such an outlet structure forcovered hopper railway cars which has a pneumatic discharge nozzlearranged in such a manner as to utilize only a minimum vertical spacebetween the bottom of the hopper structure and the supporting trackstructure thereby permitting maximum utilization of the cubic capacityof the hopper car.

A further object is the arrangement of a hopper structure in whichpulverulent material is pneumatically unloaded in a generally mass flowwith the material moving downwardly in a uniform manner and the uppersurface of the material remaining substantially level until unloaded.

Briefly, the invention includes a bottom outlet structure secured to theunderside of a hopper structure for pneumatically unloading materialsand having a plenum chamber formed between a permeable inner wall andthe outlet housing, the plenum chamber extending completely around theinner periphery of the outlet structure and around a discharge openingin the bottom of the outlet structure, the upper surface of the slopingpermeable inner wall leading to the discharge opening, and a dischargenozzle extending laterally from the discharge opening and fitting withinthe bottom ofthe outlet housing with a portion of the housing cut awayto receive the inlet end of the discharge nozzle. The inner permeablewall or member is easily secured in place within the outlet housing bywelding directly to the outlet housing without the use of anyintermediate gaskets or ring members to provide support for the memberand is of a sutficient rigidity to support the material to be unloadedwithout undue wear even though a relatively large sup port area isprovided. The exposed surface of the permeable wall is relatively denseand smooth to permit material to slide easily over the surface and toallow cleaning of the surface with strong solvents or steam. By havingthe discharge nozzle extending laterally from the outlet housing, only arelatively small vertical space is utilized by the outlet structure andthe hopper structure may extend downwardly to a maximum extent.

or angle relative to the horizontal thereby to effect a mass flow of thematerial and a relatively fast movement of material along the surfacesto the outlet structure.

The invention accordingly comprises the constructlons hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

In the accompanying drawings, in which several of various possibleembodiments of the invention are illustrated,

FIGURE 1 is a side elevational view of the present inventionillustrating a plurality of outlet structures comprising one embodimentof this invention mounted on the bottom of a covered hopper railway car;

FIGURE 2 is a partial elevational view of the railway car of FIGURE 1with a portion thereof broken away and illustrating one of the hopperstructures;

FIGURE 3 is an end elevation of the railway car of FIGURES 1 and 2 witha portion thereof broken away; FIGURE 4 is a plan view of the outletstructure shown in FIGURES 1-3 removed from the hopper structure;

FIGURE 5 is a sectional view taken generally along line 55 of FIGURE 4;

FIGURE 6 is a sectional view taken generally along line 66 of FIGURE 4;

FIGURE 7 is a sectional view taken generally along line 7-7 of FIGURE 4;

FIGURE 8 is a sectional view similar to FIGURE 6 but showing a dischargenozzle removed from the bottom of the outlet structure;

FIGURE 9 is a plan View of the discharge nozzle shown in FIGURE 8;

FIGURE 10 is a side elevational view of the discharge nozzle of FIGURE9;

FIGURE 11 is an end elevation of the discharge nozzle of FIGURES 9 and10 with a portion thereof broken away and taken generally along line1111 of FIGURE 10;

FIGURE 12 is an enlarged fragment of the connection of the outletstructure to the hopper structure and showing the permeable wall securedadjacent thereto;

FIGURE 13 is an enlarged fragment in elevation of a rib supporting thepermeable member;

FIGURE 14 is a section taken generally along line 14-14 of FIGURE 13;

FIGURE 15 is a plan view of the permeable member showing a membranebroken away and illustrating the rigid base therebeneath;

FIGURE 16 is a schematic view showing the piping arrangement for thecovered railway hopper car and outlet structures shown in FIGURE 1;

FIGURE 17 is a plan view of a separate embodiment of the outletstructure adapted to be removably secured to the bottom hopper structureof a railway car or the like;

FIGURE 18 is a sectional view taken generally along line 1818 of FIGURE17;

FIGURE 19 is a sectional view taken generally along line 19--19 ofFIGURE 18 and showing the discharge nozzle removed;

FIGURE 20 is a side elevation of the discharge nozzle of FIGURE 19;

FIGURE 21 is a plan view of the discharge nozzle shown in FIGURE 20;

FIGURE 22 is an end elevation of the discharge nozzle of FIGURES 20 and21;

FIGURE 23 is a perspective of a modification of the permeable memberemployed in the bottom outlet structures of FIGURES 116 and FIGURES17-22; and

FIGURE 24 is an enlarged fragment of a modified construction forsecuring the permeable member within the outlet structure.

Referring to the embodiment shown in FIGURES 1-16 of the drawings andparticularly FIGURES 1-3, a covered hopper railway car is generallydesignated 10 and is of the type to which the present invention isapplicable. Car 10 includes a plurality of contiguous hoppers or hopperstructures 12 separated by bulkheads 14 extending only partially to thetop of car 10. Bulkheads 14 serve to strengthen the sides of the car andto minimize the spill-over between adjacent hopper structure 12. Apartial cylindrical shell 15 forms the roof and upper sides of car 11).End slope sheets 16 extend downwardly to end hoppers 12 at an angle ofaround 60 with respect to the horizontal. A side sheet 17 on each sideof car 10 extends downwardly from partial shell 15 and each sheet 17 isdisposed at an angle of around 70 with the horizontal. The inner surfaceof each hopper 12 funnels downwardly from a generally rectangular upperopening adjacent bulk head 14 to a generally elliptical lower opening 18which extends transversely of car 10 beyond the extent of wheels W. Theinner surface of each hopper structure 12 which surrounds opening 18 isa smooth arcuate surface. Extending outwardly about the periphery ofeach opening 18 is a horizontal flange 20. Bulk material may be loadedwithin hopper car 10 through suitable openings beneath hatch covers 19.

Secured to each flange 20 is an outlet structure generally designated22. Bulk or finely-divided materials to be pneumatically unloaded, suchas granular or pulverulent materials, pass through opening 18 into therespective outlet structure 22. Each outlet structure 22 is positionedcentrally of the Width of car 10 and is generally panshaped ordish-shaped to form a relatively smooth, arcuate and shallow inner area.As outlet structure 22 is of a shallow pan-shaped outer contour, only arelatively small vertical space is employed beneath the adjacent hopper12. Thus, hopper 12 may extend downwardly a maximum'distance withinspecific clearance requirements to permit a relatively large hoppercapacity.

In order to obtain a mass flow of material into the outlet structuresfrom hoppers 12, side sheets 17 and end slope sheets 16 are relativelysteep. Mass flow is defined as a condition under which all of the bulkmaterial within a specified hopper moves downwardly uniformly with thetop or upper surface of the material in the hopper remainingsubstantially level during the unloading operation regardless of theamount of material remaining in the hopper. A minimum angle greater than50 with respect to the horizontal is necessary for the surfacestunneling into outlet structures 22 in order for finelydivided materialto have a mass flow into the outlet structures. It is to be understoodthat any desired number of outlet structures 22 may be provided onrailway car 10.

Referring to FIGURES 4-7 in which a single outlet structure 22 isindicated, each structure 22 has a body housing 24 with an upperperipheral flange 26 secured by suitable bolt and nut combinations 28 toflange 20. Sloping downwardly from flange 26 is a peripheral shoulder 30forming an inner ledge or seat. A circumferential rim 32 extendsdownwardly from shoulder 30 and a body portion 34 slopes inwardly fromrim 32 at a relatively small degree of inclination. Inclinations betweenabout 5 and 30 form generally shallow panshaped outlet structures andwill function effectively while utilizing a relatively small verticalspace. As outlet structure 22 is generally oval-shaped, the slope of theoutlet structure varies from a maximum along the transverse center linethereof as shown in FIGURE 5 to a minimum along the longitudinal centerline thereof as shown in FIGURE 6. Thus, the slope is constantly andgenerally uniformly decreasing for each quadrant from the transversecenter line along line 5-5 of FIG- URE 4 to the longitudinal center linealong line 6-6 of FIGURE 4.

It is desirable to have an outlet structure extending transversely ofthe car to a maximum extent in order to provide a maximum cubic capacityor volume in hopper car and to obtain a relatively low center of gravityin the loaded car. Each outlet structure 22 extends transversely of thecar beyond wheels W as shown in FIGURE 3 so that hopper structures 22may be of a maximum dimension transversely of car 10. The dimension ofeach outlet structure 22 longitudinally of car 10 is denoted as thewidth of outlet structure 22 and is substantially smaller than thelength of outlet structure 22 which extends transversely of the car.

Sloping downwardly from shoulder 36 to an elongate outlet dischargeopening 36 and secured to a main body portion 34 are a plurality ofgenerally T-shaped ribs each generally designated 38. Each rib 38 has anupper flange 39 and a web 40 with a plurality of apertures 42therethrough, see FIGURES 13 and 14. Each web 40 is welded to bodyportion 34. To form elongate opening 36, a portion of body portion 34 iscutaway at 44 as shown in FIGURE 4. Fitting within cutaway portion 44 isa discharge nozzle generally designated 46 which is secured, such as bywelding, to housing 24 (see FIG- URE 4). Nozzle 46 is a cast structureand is welded to housing 24.

Referring to FIGURES 81l particularly, nozzle 46 includes a plate-likeextension 48 having a generally fiat bottom 59 beneath outlet opening 36and an upper circumferential wall 52 defining the discharge opening 36extending around bottom 50. Extending from extension 48 is a tubularportion 54 having an inlet opening 56 of an inner generally ellipticalcontour and an outlet opening 58 of an inner generally circular contour.Inlet opening 56 extends through the adjacent portion of wall 52. Theinner peripheral surface of tubular portion 54 gradually changes from anelliptical contour at inlet opening 56 to a circular contour at outletopening 58. This arrangement permits outlet structure 22 to be mountedin a minimum vertical space. Projecting from the upper surface oftubular portion 54 is a T-shaped rib 38 which fits adjacent a T-shapedrib 38 mounted on body portion 34 to form a smooth continuation thereofas shown in FIGURE 4. Extending downwardly from the outer end ofT-shaped rib 38' is an outer shoulder 66 fitting against and secured tohousing 24. Extending downwardly from the inner end of T-shaped rib 38is an inner shoulder 68 formed by the adjacent wall 52. Shoulder 66 iswelded to the adjacent edge of body portion 34 for holding and securingnozzle 46 in position.

Mounted on ribs 38 are eight generally triangularshaped segments 72 eachsegment extending between two adjacent ribs as shown in FIGURE 4.Segments 72 form a permeable member which extends circumferentiallyaround the inner periphery of housing 24 to define a plenum chamber 76between segments 72 and the inner surface of housing 24. The areabeneath rib 38' is also a portion of chamber 79. Each segment 72 isformed of an upper permeable membrane 74 and a lower supporting base 76which has a sufiicient rigidity to support membrane 74 between adjacentribs 38 when material is supported on the upper surface of membrane 74and air under pressure is supplied to plenum chamber 70 through an airinlet conduit or pipe 75. Membrane 74 is formed of a fiber metalmaterial in which metallic fibers having a length to diameter ratio ofat least ten to one, and a high as two thousand to one, are individuallydispersed and felted to form a random, interlocked non-woven body. Thenon-woven body is then sintered under reducing conditions at a hightemperature to produce welds or metallic diffusion bonds at interfibercontact points. The sintered fiber metal forming membrane 74 isrelatively dense but yet is permeable to allow a generally uniformintroduction of fiuidizing air from plenum chamber 70. Thus, theporosity of membrane 74, defined as the percent ratio of pore space byvolume 6 to the entire volume of the membrane, is relatively small.

Base 76 may be formed, for example, of stainless steel having aplurality of apertures 78 therethrough to permit air under pressure fromplenum chamber 70 to pass through apertures 78 and membrane 74. The areaof base 76 over nozzle 46 is not perforated for around two inches frominlet 56 so that air will not interfere with the material entering inlet56. Membrane 74 may be suitably secured to base 76, for example, by anadhesive such as a thermosetting liquid adhesive, or by sinteredbonding.

The resistance to the passage of air through a porous medium mayconveniently be expressed in terms of air volume passing at a specifiedpressure drop across the medium. The term permeability is commonlyemployed as illustrative of this method and is defined as the amount ofair measured in cubic feet and at 70 F. and 25% relative humidity whichwill pass through the area of one square foot of the membrane in oneminute when tested under an equivalent pressure differential of twoinches of water. A permeability of around 10 has been found to beeffective for unloading the bulk material in railway car 10. This ratingmay be obtained by employing a membrane 74 of around ,4 of an inch inthickness and a stainless steel base 76 of around inch in thickness withapertures 78 including around 60% of the entire surface area of base 76.

Referring to FIGURE 12, base 76 of each segment 72 has an upper marginalportion 79 seated on shoulder 30 and welded thereto as indicated at 80.A lower marginal portion 81 of each segment 72 (see FIGURES 4 and 8) issecured, such as by welding, to the upper surface of wall 52. Membrane74 has its upper edge 82 spaced downwardly from weld as shown in FIG-URE 12. Adjacent segments 72 are spaced slightly from each other overeach rib 38. Adjacent metal bases 76 extend laterally beyond thesuperjacent membranes 74 and are welded at 83 to the upper surface offlange 39 as shown in FIGURE 14.

It is not necessary for base 76 and membrane 74 to be tightly secured toeach other except along the upper and lower edges of the membrane aslateral air flow between membrane 74 and base 76 is not undesirable,unless, of course, the air leaks considerably between membrane 74 andbase 76 adjacent upper edge 82 and lower marginal portion 81 (see FIGURE8).

Metallic base 76 permits the permeable member or wall to be weldedpermanently in place while the inner surface of membrane 74 which is incontact with the lading to be unloaded is relatively smooth. Thus, noretaining bolts or similar retaining means are required to hold membrane74 in position which might possibly interfere with the flow of materialalong the relatively smooth and dense surface of the membrane.Additionally, if it is desired to replace a defective segment 72, onlythe respective defective segment need be removed and a new segment 72may be welded into position. Since membrane 74 is relatively dense, itmay be easily cleaned with water or solvent without any resulting damageor deterioration to the membrane. The small pore size of membrane 74minimizes the filling or clogging of the pores with the material to beunloaded, such as cement. Also, the path of the air passing through thesintered metal membrane is tortuous and any material which tends to fillthe pores must follow a tortuous path thereby permitting only a minimumamount of material to penetrate the surface of the membrane.

Referring to FIGURE 16, the piping system for conveying air underpressure to car 10 and for removing the lading from the car is shown.Air under pressure is sup plied at either inlet 88 of pipe 90 from asuitable low pressure air source (not shown) of around 15 psi. such ascommonly found on many highway trailers. Inlet pipes 75 connect to amain supply pipe 92'and each has a valve 94 therein to selectivelycontrol the supply of air to the plenum chamber of each outlet structure22. Each valve 94 also includes a check valve. Air is also supplied frominlet 88 to a lading discharge pipe 96 which has an outlet 97 throughwhich the material is discharged from car 10 to a suitable storagefacility (not shown). Nozzles 46 are each connected to discharge pipe 96and each nozzle has a discharge valve 98 so that the flow of materialfrom each outlet structure 22 may be selectively controlled. A mainvalve 100 in pipe 96 selectively controls the flow of air through pipe96 for unloading car 10.

Operation is as follows:

A suitable source of air under pressure is connected to inlet 88 withvalve 100 closed and all valves 94 for the plenum chambers 70 beingopened to permit air under pressure in the plenum chambers. A suitableconduit (not shown) is connected to outlet 97 and leads to a suitablestorage facility. Air from each plenum chamber 70 permeates theassociated membrane 74 and mixes with the material or lading adjacentthe membrane. The pulverulent material is fluidized so that it behaveslike a liquid by reducing the internal strength of the mass of material.The air pressure within car It gradually increases after inlet 88 isconnected to an air source and upon reaching around 14 p.s.i., valve 100is opened to permit air within pipe 96, valves 98 remaining closed. Tocommence the discharge of the lading, the first two valves 98 adjacentoutlet 97 are opened and the lading is unloaded through the associatednozzles 46. The outlet structure 22 closest adjacent outlet 97 will beunloaded first, and then the lading is unloaded immediately from thenext succeeding outlet structure 22, the valve 98 being closed for theoutlet structure 22 which has been unloaded and the next succeedingvalve 98 being opened. Thus, a continuous flow of lading is providedfrom one hopper structure 12 to the next. After all of the outletstructures 22 have been emptied, a relatively complete cleanout ofmaterial may be effected by opening each valve 98 individually for a fewseconds. It is to be understood that plenum valves 94 may in someinstances, such as during operation with a limited air supply, beoperated simultaneous with the respective associated valve 98.

A relatively small period of time is requird to unload as a uniform massflow of material is obtained. During unloading of a hopper, the uppersurface of the lading in the hopper remains generally level during allstages of unloading. This is important as car 10 is under air pressurewhen being unloaded and aids in assisting the material toward the outletstructure. If the material un loads unevenly, air above the materialwill communicate directly with the outlet opening before the car isfully unloaded. A relatively large amount of material usually remains inthe outlet structure 22 when mass flow is not effected. Once directcommunication is effected between air within the car and the outletopening, the remaining material may only be unloaded by gravity flow tothe outlet opening where it is entrained in a high velocity air streamwhich results in undesirable dusting and an inefficient employment ofavailable air.

Referring to FIGURES 17-22, another embodiment of an outlet structure isillustrated in which outlet structure 22A is of a generallyfrusto-conical shape. Four segments 72A are secured, such as by welding,to ribs 38A secured to housing 24A. Segments 72A are formed in a mannersimilar to segments 72. Air under pressure is supplied to plenum chamber70A through an inlet pipe 75A. As outlet structure 22A is frusto-conicalin shape, the slope of segments 72A is generally uniform about theentire inner periphery of outlet structure 22A. A portion of housing 24Ais cut away to receive discharge nozzle 46A which is secured, such as bywelding, to housing 24A. Discharge nozzle 46A has a plate-like extension1112 generally circular in outer contour and forming a bottom for bottomopening 104. A tubular portion 106 of discharge nozzle 46A has acircular contour. Segments 72A are secured to the upper surface of wall52A which extends around the outlet opening.

Referring to FIGURE 23, a separate embodiment of a permeable member isillustrated in which the separate metallic base 76 illustrated inFIGURES ll6 is eliminated. Permeable member indicated generally 198 hasa wire fabric of a fine mesh pressed into the permeable fiber metalmembrane 74A on each surface thereof during the sintering operation.VJire fabric 110 provides adequate rigidityfor membrane 74A and may beWelded directly to housing 24 or 24A as is permeable member 72 of theembodiment illustrated in FIGURES 1-16.

Referring to FIGURE 24, another construction for securing the upperportion of the permeable member in position is illustrated whicheliminates welding of the permeable member to shoulder 30. Metallic base76B has a generally horizontally extending rim 112 about its peripheryfitting between flange 20 of hopper structure 12 and flange 26 of outletstructure 22. A suitable gasket 114 is positioned on each side of rim112. Membrane 74B is secured, such as by a thermosetting adhesive, tobase 76B to form a permeable wall. Metallic base 763 may be easilyclamped between flanges 20 and 26 without welding. The lower portion ofthe permeable member is secured similarly to the embodiment of FlGURESll6.

While outlet structure 22 has been illustrated particularly foremployment with a covered hopper railway car, it is to be understoodthat outlet structure 22 may be employed with other types of hopperstructures, such as hop per structures on highway trailers or the like.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous result-s attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1. A bottom outlet structure adapted to be secured beneath an opening inthe bottom of a hopper to receive and effect pneumatic discharge ofmaterial from the hopper through the opening, said bottom outletstructure comprising a generally oval, pan-shaped housing tunnelingdownwardly to a bottom discharge opening and adapted to communicate withthe opening in the bottom of the hopper for receiving materialtherefrom, a gas permeable member fitted within the housing and beinggenerally funnel-shaped to provide inner surfaces converging from theopening in the hopper, said gas permeable member being spaced inwardlyfrom the housing to form a plenum chamber extending circumferentiallybetween the housing and the gas permeable member and adapted tocommunicate with. a source of gas for supplying gas under pressure tothe plenum chamber, said gas permeable member comprising a gas permeablemembrane on the upper side thereof and a generally rigid base on thelower side thereof having a plurality of apertures therethrough, acircumferential wall projecting generally upwardly from said housing toform said bottom discharge opening, a plurality of support ribs in theplenum chamber extending longitudinally generally radially from saidcircumferential wall and supporting the gas permeable member, said ribshaving air passages there through to permit a substantially free flow ofair about the circumferential wall, said base being secured along itsupper marginal portion to the housing and having a lower marginalportion secured to said circumferential wall and extending around thebottom discharge opening, said housing having a portion thereof cutawayadjacent the discharge opening, and a discharge nozzle received withinsaid cutaway portion and extending generally in a horizontal directionfrom the bottom discharge opening whereby material being unloaded movesalong the permeable member to the bottom discharge opening.

2. An outlet structure as set forth in claim 1 wherein said housing hasan outer flange extending around its upper periphery and a downwardlysloping inner surface adjacent said outer flange forming a smooth ledgethereon, and said permeable member comprises a permeable membrane on theupper side formed of a sintered fiber metal and a metallic base on itslower side adjacent the permeable membrane, said metallic base havingits upper marginal portion secured to said ledge and having a pluralityof apertures therethrough to permit the passage of air from the plenumchamber.

3. An outlet structure as set forth in claim 2 wherein said permeablemember is divided into a plurality of generally triangularly-shapedsegments each supported on and secured to at least one of said supportribs.

4. A covered hopper railway car for carrying and unloadingfinely-divided materials comprising a hopper structure having downwardlydirected surfaces disposed at an angle of at least 50 with respect tothe horizontal and funneling through a bottom opening, a bottom outletstructure removably secured beneath the opening in the hopper structureto receive and effect pneumatic discharge of the material received fromthe hopper structure, said bottom outlet structure comprising agenerally pan-shaped housing funneling downwardly to a bottom dischargeopening and communicating with the opening in the hopper structure toreceive material therefrom, a gas permeable member fitting within thehousing and being generally funnelshaped to provide surfaces convergingfrom the opening in the hopper structure, said gas permeable memberbeing spaced inwardly from the housing to form a plenum chamberextending circumferentially between the housing and the gas permeablemember, said gas permeable member comprising a gas permeable membrane onthe upper surface thereof and a generally rigid base on the lowersurface thereof having a plurality of apertures therethrough, acircumferential wall projecting generally upwardly from said housing toform said bottom discharge opening, a plurality of support ribs in theplenum chamber extending longitudinally generally radially from saidcircumferential wall and supporting the gas permeable member, said ribshaving air passages therethrough to permit a substantially free flow ofair about said circumferential wall, said housing having a portionthereof cutaway adjacent the bottom discharge opening, said gaspermeable member having a lower marginal portion secured to saidcircumferential wall around the entire periphery of the bottom opening,a discharge nozzle received within said cutaway portion and extendinggenerally in a horizontal direction from the discharge opening, andmeans to supply gas under pressure to the plenum chamber at a suflicientrate to free any finely-divided material adjacent the gas permeablemember whereby the material moves downwardly along the inner surfacethereof to the discharge opening.

5. A covered railway hopper car for carrying and unloadingfinely-divided materials as set forth in claim 4 wherein said generallypan-shaped housing has an outer flange extending around its upperperiphery and a downwardly sloping inner surface adjacent said outerflange forming a smooth ledge thereon, said permeable membrane beingsintered fiber metal and said base being a steel sheet metal havingsufiicient rigidity to withstand the weight of the material on themembrane and the air pressure within the plenum chamber, said basehaving its upper marginal portion secured to said ledge to hold thepermeable member in position.

6. A covered hopper railway car for carrying and unloadingfinely-divided material as set forth in claim 5 wherein said permeablemember is divided into a plurality of generally triangularly-shapedsegments each supported on and secured to at least one of said supportribs.

7. A covered hopper railway car for carrying and unloadingfinely-divided materials comprising a hopper structure having downwardlydirected surfaces disposed at an angle of at least with respect to thehorizontal and funneling into a generally elliptical bottom openinghaving a peripheral outer flange therearound, a bottom outlet structurebeneath the opening in the hopper structure to receive and effectpneumatic discharge of material from the hopper structure, said bottomoutlet structure comprising a housing being generally of an ovalpanshape and funneling downwardly to an elongate bottom dischargeopening, the housing having a length extending transversely of the carto an extent beyond the wheels on each side of the railway car, an upperperipheral flange on said housing adapted to be secured to said outerflange of the hopper structure adjacent said generally elliptical bottomhopper opening, a gas permeable member mounted within the housing andforming a plenum chamber between the gas permeable member and thehousing, means in the plenum chamber between the permeable member andsaid housing for supporting the permeable member, a circumferential wallprojecting generally upwardly from said housing to form said bottomdischarge opening, said permeable member having a lower margin-a1portion secured to the upper surface of said circumferential wall aboutthe entire periphery of the elongate bottom outlet therein, said housinghaving a portion thereof cutaway adjacent the discharge opening, and adischarge nozzle received within said cutaway portion and extendinggenerally in a horizontal direction from the elongate bottom openingwhereby material being unloaded moves along the permeable member to thebottom opening.

8. A covered hopper railway car as set forth in claim 7 wherein saidpermeable member comprises an upper permeable membrane of sintered metaland a lower supporting metal base having a plurality of apertures topermit the passage of gas from the plenum chamber through the permeablemember.

9. A covered hopper railway car for carrying and unloadingfinely-divided material as set forth in claim 7, wherein said permeablemember comprises a permeable membrane of sintered metal and a meshedmetal fabric on each side of said membrane to provide rigidity for saidpermeable member.

10. A covered hopper railway car as set forth in claim 8 wherein saidpermeable membrane is divided into a plurality of generallytriangularly-sh-aped segments each supported on said metal base.

11. A covered hopper railway car for carrying and unloadingfinely-divided material as set forth in claim 8 wherein said supportingmetal base has a peripheral rim fitting between the peripheral flangesof said housing and hopper structure, and means holding said flangestightly together for clamping said peripheral rim therebetween.

References Cited by the Examiner UNITED STATES PATENTS 2,395,727 2/1946Devol 30229 2,676,851 4/1954 Sylvest 302--29 2,924,489 2/1960 Beckmann302-53 2,975,915 3/1961 Lindley 30252 3,080,173 3/1963 Johnson et al.30252 3,180,689 4/1965 Albert 302-52 ANDRES H. NIELSEN, PrimaryExaminer.

1. A BOTTOM OUTLET STRUCTURE ADAPTED TO BE SECURED BENEATH AN OPENING INTHE BOTTOM OF A HOPPER TO RECEIVE AND EFFECT PNEUMATIC DISCHARGE OFMATERIAL FROM THE HOPPER THROUGH THE OPENING, SAID BOTTOM OUTLETSTRUCTURE COMPRISING A GENERALLY OVAL, PAN-SHAPED HOUSING FUNNELINGDOWNWARDLY TO A BOTTOM DISCHARGE OPENING AND ADAPTED TO COMMUNICATE WITHTHE OPENING IN THE BOTTOM OF THE HOPPER FOR RECEIVING MATERIALTHEREFROM, A GAS PERMEABLE MEMBER FITTED WITHIN THE HOUSING AND BEINGGENERALLY FUNNEL-SHAPED TO PROVIDE INNER SURFACES CONVERGING FROM THEOPENING IN THE HOPPER, SAID GAS PERMEABLE MEMBER BEING SPACED INWARDLYFROM THE HOUSING TO FORM A PLENUM CHAMBER EXTENDING CIRCUMFERENTIALLYBETWEEN THE HOUSING AND THE GAS PERMEABLE MEMBER AND ADAPTED TOCOMMUNICATE WITH A SOURCE OF GAS FOR SUPPLYING GAS UNDER PRESSURE TO THEPLENUM CHAMBER, SAID GAS PERMEABLE MEMBER COMPRISING A GAS PERMEABLEMEMBRANE ON THE UPPER SIDE THEREOF AND A GENERALLY RIGID BASE ON THELOWER SIDE THEREOF HAVING A PLURALITY OF APERTURES THERETHROUGH, ACIRCUMFERENTIAL WALL